The field of orthodontics is concerned with repositioning and aligning a patient's teeth for improved occlusion and aesthetic appearance. For example, orthodontic treatment often involves the use of tiny slotted appliances, known as brackets, which are fixed to the patient's anterior, cuspid, and bicuspid teeth. An archwire is received in the slot of each bracket and serves as a track to guide movement of the teeth to desired orientations. The ends of the archwire are usually received in appliances known as buccal tubes that are secured to the patient's molar teeth.
An orthodontic anchor, such as a temporary anchorage device (TAD), may be used in combination with a bracket and wire orthodontic system to aid orthodontic tooth movement. A TAD is also referred to as a microimplant or microscrew due to the typical screw-like shape of the device. By acting as a rigid point of support for an orthodontic system, a TAD is useful for achieving forces in a direction not easily obtained with traditional bracket and wire systems. For example, one or more TADS may be surgically implanted in a jaw bone (i.e., the mandible and/or maxilla) of a patient to provide an anchor for a traction element (e.g., a wire or elastic band) that retracts a patient's front teeth inward (i.e., toward the molars). TADs may be used in place of or in addition to head gear, which is a conventional device for aiding orthodontic tooth movement.
In one conventional technique for implanting a TAD, an orthodontic practitioner drills a pilot hole in a patient's jaw bone between the roots of teeth, and subsequently screws the TAD into the pilot hole with a tool such as a small screw driver or small ratchet wrench. Alternatively, the orthodontic practitioner may utilize a TAD that is self-tapping and does not require a starter hole in order to be implanted in a patient's jaw. A typical TAD is about 4-5 millimeters in length, but the length varies based on a variety of factors, such as the TAD application.
One important consideration when choosing an implant site and orientation of the TAD is the location of the roots of the patient's teeth. For many reasons, it is preferable to avoid perforating a root with the TAD.